Tool and Cutter Grinder Can’t Swivel Head

[extropic]

David,
First I applaud you for not forcing the suspected worm mechanism. IMHO, forcing it would almost guaranteed catastrophic damage.
I suspect that the two grub screws are a type of "Scotch key" which both prevent rotation of the worm bushing and retain it in the housing.
My bet is, if you remove those two grub screws, turning the hex head (in the correct direction) will lift the worm and bushing right out of the housing.

As for the locking bolt: it makes sense to me that it would be a split cotter. Can you see the end opposite the bolt head or is it all in a blind hole?
If the opposite end is visible (not a blind hole) remove the bolt and both parts of the split cotter. If it's a blind hole, I'd keep tapping the lower part of the split cotter (nut) down to be certain it's disengaged. Then remove the bolt and fish out the upper part of the split cotter. The next step is to apply a liberal amount of penetrating oil and let soak for a day or two.

In case you're not familiar with the term "split cotter" THIS should clarify it. I Googled "split cotter" but found only cotter pins (split pins). No help in Wikipedia either. I must have weak Google fu today.

In your picture I see a hole that looks like it's directly over the axis we're trying to free up. What's the hole for? Possibly a dog point grub screw (running in a groove on the shaft) to retain the shaft (but BOZO has over-tightened it)? What do you see when you look in the hole? Is the hole through to the rotating shaft? Fill the hole with penetrating oil???

If you do all of the above and it won't free up after a day or two soak, I would warm the housing with a hot air gun to 200-300F and add more penetrating oil. Repeat the heat/oil cycle a few times a day for a few days.

Good luck.
Edited for spelling

 

[Cadillac]

I have a grinder that is very similar but has subtle differences. What I would think is the threaded hole has a setscrew that engages in a groove on the spindle pivot which keeps the motor tight in that joint. The screw head located on the brass bushing is what will pivot the head. The other hex would be the locking screw for the pivot Assy.
Mine doesn’t have a worm to pivot the head Assy. Mine has a setscrew to keep the pivot tight to each other and a locklever to keep the pivot from moving. Movement of the pivot is done manually no worm screw.

 

[David Pollard]

More great advice. I love this place
It is difficult to know how much force is enough on that worm screw but but I'm old enough to know a big hammer or a pipe on the spanner will destroy it. I have assumed the hole on the centre line of the shaft is an oil hole. I never thought of it possibly being a locking pin of some description. I have been squirting penetrating oil (Lanux) down there in the hope it would loosen any stuck bits. I'll put an allen key down their to see how deep it goes. Maybe a bright like and a bit of a look. It's only about a 5mm hole and it may be threaded. Not sure, I'll take a closer look at that.

As for the locking bolt at the back it is completely captured at the bottom. I unscrewed the bolt completely and it lifted out.
Following more advice I did the tapy tapy thing with the bolt only loosened one turn and it did not seem any any way tight or stuck but it did seem to lower whatever is screwed onto the bolt each time I taped it.
I didn't want to keep loosening and tapping as I didn't want whatever is going on in there to fall off the bottom into some kind of blind hole.

I haven't seen those split cotter locks before (reviewing your link). They look very effective. From memory, not that I examined it very closely I think the bolt looked just like a bolt when I withdrew it from the hole. It seems free and happy.

I'm starting to suspect there is a locking pin down that hole now. The small one on the centre line of the pivot.

Cadillac, Your machine looks like it is in great shape! Yes it is quite similar to mine.
I'm a Fitter and Turner trained back in the 80's. I'm in IT now (30 years) but having a great time building up my F&T tools in my shed and getting back into it. I never used a T&C grinder in those days. Just watched other people so I have a bit of a learning curve ahead of me.

 

[David Pollard]

Update:
I had a look down that little hole and there is no thread.
It looks like the bottom of the hole surface is the circumference of the horizontal shaft.
It may be for a missing lock pin but I can’t see anything in the bottom of the hole for the pin to drop in to.
Just a little pool of Lanux
so it looks to me like this hole isn’t locking the rotation in any way.

 

[Downunder Bob]

Update:
I had a look down that little hole and there is no thread.
It looks like the bottom of the hole surface is the circumference of the horizontal shaft.
It may be for a missing lock pin but I can’t see anything in the bottom of the hole for the pin to drop in to.
Just a little pool of Lanux
so it looks to me like this hole isn’t locking the rotation in any way.

G'day, the Lanux you are referring to, Are you sure you don't mean Lanox, Lanox MX4 I am familiar with, and I use it, but more as a protecting rust preventer. I think you will find it's sister product Inox MX3 is a far better penetrant In my opinion the best there is. Good luck with your project.

 

[extropic]

Assuming there are no other features (not shown in the photos) to investigate, My recommendation is to remove the worm/bushing and all of the locking mechanism that you can. Then, penetrating oil + heat/cool cycles until it surrenders.

That hole on top probably should receive an oil cup (or at least a removable plug) when you're ready to reassemble.

 

[David Pollard]

Hi Extropic,
Yes it is Lanox, I couldn't be bothered checking the spelling. I do know Inox as well but don't have any at the moment.
I'll have to get some.

The heat cool sounds like the next best step as there are no other features. I'll have to pick up a proper heat gun. I don't want to torch it
I'll post again once something interesting happens.

There must be a mechanism somewhere to adjust the end play and hold it all together.

Thanks for all the advice
David

 

[David Pollard]

SOLVED!
=========

I went out and bought some Inox and a heat gun.
As it turned out I didn‘t need the heat gun. I was a bit concerned I‘d burn the paint off anyway.
I removed the lock bolt and gave it a blast with Inox.
I removed the two little grub screws that were only in a couple of turns. I could then use the worm gear to push out the brass bush that was held in by the grub screws. Another blast of Inox down that hole.
I gave it a reasonable whack with a wooden Mallet in each direction and it moved 0.5 degrees.
More tapping back and forth and it freed right up.
For any one else facing the same problem.
Remove the whipper seal and slide it up the column. It overlaps the brass bush on the worm shaft by about 0.5mm and it shaved a nice flat onto that bearing as I cranked it out. (no serious damage)
When reassembling it was a bit of a job lining up those two little scotch key grub screws. I used the motor itself to pull that bush back into the hole and just took up the free play on the worm each time. This avoided twisting the bush and misaligning those little threads.
I could then screw the grub screws all the way back in with no undue force.

By the way, there were some kind of notches down that plain hole in the middle.
One at 60 deg either side of 0 And one at 180 deg but strangely not at zero. I think I’ll just make a dust plug for it and we can call it an oil hole. Maybe one day If i ever have the shaft out and can tell exactly what’s going on down there I’ll do something different.

Now I’m running out of reasons not to make some sparks.
Oh, I need to make a wheel dresser.
Thanks again guys for all your suggestions!